Welder&#39;s helmet

ABSTRACT

A welder&#39;s helmet (1) provided with a fast filter (3) which is controlled by welding light and through which the wearer of the helmet can see clearly in the absence of welding light. In accordance with the invention, the helmet is complemented with side windows (4) operative to filter out IR and UV radiation and having a moderate filter effect for visible light.

The present invention relates to welder's helmets of the kind which arefitted with so-called fast filters, i.e. a light filter which remainscomparatively clear until subjected to the effect of welding light,whereupon the filter darkens, normally through switching of thepolarization of one or more liquid crystal layers in combination withpolarizing filters.

Helmets that are fitted with permanent filters are used solely during anactual welding operation, and when no welding is in progress, thefilters, and possible also parts of the helmet, are moved out of theway. Welder's helmets fitted with so-called fast filters, however, arenormally worn constantly during work and may often be provided,comfortably, with "air conditioning" and perhaps also with earphones orhearing protectors, these facilities being appreciated in someindustrial environments.

One drawback with helmets of this kind is that because the wearer canonly see straight ahead through the fast filter, he loses thecomprehension of space. Many workmen find this uncomfortable and thelowered perception may result in an accident or injury.

An object of the invention is to provide an improvement in this regard.This object is achieved in accordance with the invention with a welder'shelmet having the characteristic features set forth in claim 1.

Thus, according to the invention, separate filter windows are disposedon respective sides of the fast filter. These windows will preferablyhave a given filter factor, in order to give equilibrium and freedomfrom dazzle. The welding light generated will result in significantillumination of the surroundings, as will also the light generated byother welding operations, particularly in workshops in which severalwelders are at work. Accordingly, the filter windows will preferablyhave a given filter effect in the visible range and will also preferablygive low transmission in the UV-range and in the IR-range.

Known to the art are welder's helmets that are fitted with conventionalfilter glass and which have a large, integrated front window. This frontwindow has a higher density in the center thereof, so as to protect thewearer against welding light which falls immediately on the eyes, and alower density at the sides of the window. One problem with a helmetconstruction of this kind is that direct welding light will enter thehelmet and illuminate the face of the wearer, such that the face becomessuffused with light within the helmet. The illuminated face of thewearer of the helmet is reflected in the rear side of the filter part ofhigher density, therewith decreasing the contrast. Furthermore, thegeneral brightness to which the eyes are subjected causes the eyes toadjust to an excessively high light density. When the welding operationhas been completed, it takes time for the eyes to adjust to the reducedbrightness. An object of the invention is to improve the field ofvision, without suffering these drawbacks.

BRIEF DESCRIPTION OF THE DRAWING

The invention will now be described in more detail with reference to anexemplifying embodiment thereof and with reference to the accompanyingdrawing, which illustrates a welder's helmet.

DETAILED DESCRIPTION OF THE INVENTION

The welder's helmet 1 illustrated in the drawing comprises a curved,plastic face mask. The helmet further comprises a head strap 2 which istightened around the head of the wearer, so as to support the helmet.The face mask is pivotally attached to the head strap at two pointsthereon, one of said points being referenced 5 in the drawing while theother point on the other side of the face mask is not visible in thedrawing. The face mask can thus be pivoted about these pivotattachments, so as to enable the mask to be raised and leave the facefree.

The helmet further includes a framed welding glass 3 which is mountedopposite the position of the wearer's eyes. This glass is of thefast-filter type and may be a filter glass of the kind marketed by usunder the trademark "Speedglas", which comprises in sequence aninterference filter which will solely allow visible light to passthrough and a combination of polarization filters and liquid crystallayers controlled by a light sensor (not shown) so as to darken theglass quickly upon the occurrence of welding light, as described inSE-A-7804630-7.

The face mask has provided on respective sides of the welding glass 3side openings in which side filters 4 are fitted. These side filters areoperative to filter-out IR and UV radiation and have a visual filtereffect of, e.g., between 4 and 5 degrees of density.

The degree of density is defined conventionally as ##EQU1## where T isthe relative transmission.

Since the glass light filters are of conventional design, they may bemanufactured as curved so as to conform to the curved shape of the facemask 1. It is important that the filters are oriented and positioned sothat light from the weld source will not enter directly from the front,but solely from radiation spread to the surroundings from the weldinglight source, and dampened so that the helmet interior will not becometoo illuminated.

The inventive helmet can be combined with different kinds of knowndevices, such as air-exchange devices, with or without air filters,earphones, etc., and as a result of the provision of side windows, thehelmet will be far more comfortable to the wearer than a helmet whichsolely includes the central window glass. The inventive helmet can thusbe worn advantageously over long periods without causing discomfort,even by workmen who would otherwise feel discomfort when wearing suchhelmets and who might even suffer psychological problems of a lightclaustrophobic nature. The inventive welder's helmet may also becombined with a protective helmet of the kind which covers the head, soas to protect the head against injury from mechanical sources.

I claim:
 1. A welder's helmet comprising a front surface and oppositeside surfaces, and provided on said front surface with at least oneso-called fast filter which assumes an increased optical density inresponse to welding light incident thereon, each of said opposite sidesurfaces being provided with separate side windows fitted with filterswhich will essentially exclude IR-radiation and UV-radiation and have apredetermined constant filter effect for visible light, said frontsurface being free of transparent regions other than said at least onefast filter.
 2. A welder's helmet according to claim 1, characterized inthat the filter effect of the filters in the respective side windows hasa degree of density of 4-5.